Acquired cold urticaria is a condition characterized by the onset of pruritic hives, swelling, and occasional severe systemic reactions, during the rewarming phase, after cold exposure. Pulmonary thromboendarterectomy (PTE) is a cardiac surgical procedure where organized thrombus is excised from the pulmonary vasculature in order to improve pulmonary blood flow and relieve pressure on the right ventricle. A PTE requires institution of deep hypothermic circulatory arrest (DHCA) in order to reduce blood flow from collateral vessels during thrombus excision. We describe a case of PTE performed under DHCA in a patient with ACU.